Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

652
FXUS63 KLOT 131134
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
634 AM CDT Sat Jun 13 2026

.KEY MESSAGES...

- Scattered thunderstorms late this afternoon through early
  Sunday morning. A few storms could be strong to severe.

- Possible dangerous swimming conditions at Indiana Lake
  Michigan beaches Sunday.

- Cooler temperatures early next week with precipitation
  chances returning midweek.

&&

.DISCUSSION...
Issued at 210 AM CDT Sat Jun 13 2026

Overall confidence remains low for convective/precip trends
later today into tonight. This morning is expected to be dry
areawide and then there will be a low chance (20%) for showers
and thunderstorms mainly across the southern cwa this afternoon.
As a cold front approaches the area this evening, that seems to
be the best time window for thunderstorms, late afternoon across
far northwest IL and then for areas along and north of I-80
during the evening. Showers may increase in coverage later this
evening and into the overnight hours with perhaps just isolated
thunderstorms at that time. The potential for a few storms to
become strong to severe remains with the best timing in the late
afternoon into the evening hours. Heavy rain and localized
flooding would also be possible with any stronger storms. End
time of the precipitation is also somewhat uncertain, ending
from northwest to southeast Sunday morning with some shower
activity still possible along/southeast of I-57 after daybreak
Sunday morning.

With the expectation that much of the daylight hours today could
be dry with at least some sunshine through early afternoon,
high temps may make a run at upper 80s for many areas today and
nudged temps up some. Southwest winds will also quickly
increase after sunrise with gusts into the 30 mph range possible
today.

A cold front will move across the area early Sunday morning,
shifting winds northerly and bringing in much cooler air. High
temps on Sunday may struggle to reach the lower 70s and likely
be dependent on how long cloud cover persists on Sunday with
some sunshine expected by afternoon. North/northwest winds may
gust as high as 30 mph on Sunday and these stronger winds will
allow waves to build across southern Lake Michigan, leading to
dangerous swimming conditions at Lake Michigan beaches in
Indiana and possibly some of the Illinois beaches depending on
the exact wind direction.

No significant changes in the models for the pattern next week.
An upper trough is expected to move across the Great Lakes
region midweek bringing increasing precipitation chances by
Wednesday and Wednesday night ahead of another cold front which
may bring another short burst of cooler air for the end of the
week. cms

&&

.AVIATION /12Z TAFS THROUGH 18Z SUNDAY/...
Issued at 634 AM CDT Sat Jun 13 2026

Forecast concerns include...

Chance of thunderstorms late this afternoon into this evening.
Gusty southwest winds today and gusty northwest winds Sunday.
Wind shift to north/northwest early Sunday morning.
Possible mvfr cigs tonight into Sunday morning.

Previous forecast remains on track with no significant changes
with this 12z forecast. While there remains uncertainty for
shower and thunderstorm coverage and timing later this afternoon
into tonight, latest guidance supports best timing for thunder
during the evening hours, which is covered with prob thunder
mention in the forecast. Showers may continue into the late
evening and overnight and some prob or tempo mention may be
needed with later forecasts.

Southwest winds will steadily increase through mid morning with
gusts into the mid 20kt range expected through early evening.
Winds will slowly turn westerly this evening, then shift to the
north/northwest as a cold front moves across the area early
Sunday morning. These north/northwest winds may gust into the
20kt range Sunday morning.

Mvfr cigs will be possible tonight into Sunday morning and will
be dependent on the precipitation coverage with perhaps the best
chance for mvfr cigs along and behind the cold front. Most
recent guidance suggests any mvfr cigs will be brief and opted
to maintain scattered mention for now. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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